Ultracold Neutral Plasma Produced by One-Color Two-Photon Ionization in Supersonic Nitric Oxide Molecular Beam

Nitric oxide (NO) is cooled to 1 K in a seeded Ar supersonic molecular beam. NO molecules are ionized by one-color two-photon resonant enhanced multiphoton ionization (REMPI) process to form an ultracold plasma. The density of the ionized molecules in the illuminated volume approaches to 1.5 × 10¹³ cm^?3. Prompt electrons, plasma electrons and intact NO⁺ ions are produced during this process. Experimental results confirm that the lifetime of this ultracold plasma is longer than 18.3 μs. This is the first report of NO ultracold plasma with significant lifetime produced by one-color two-photon REMPI process.